In the processing especially of terry cloth in automatic sewing installations, such as crosscutting machines, there are numerous ways of scanning the napless zones along which the cross cutting is to be affected. The known solutions work with vertically adjustable bars (e.g. German Patent 30 24 389) or with alignment beams (e.g. German open application 36 24 994), which in addition also prepare the napless stretch so that the cross-cutting takes place between the weft yarns.
Also, the lateral napless edges along a fabric web have also been scanned by means of mechanical sensors. Thereby difficulties have arisen, particularly in fast-running webs, leading to disturbances.
However, a device which can be used in textile machines for the lateral scanning of napless areas, such as particularly found in terry cloth, which proves satisfactory in all applications has not been found prior to the invention.